Anisotropic conductive film

ABSTRACT

An anisotropic conductive film which can be used as a standard product as long as no problems arise in anisotropic conductive connections, even in a case where omissions are present in a prescribed disposition of conductive particles, includes a regular disposition region in which conductive particles are disposed regularly in an insulating resin binder, and has a length of 5 m or greater. A standard region including no sections with more than a prescribed number of consecutive omissions in conductive particles is present in the regular disposition region over a prescribed width in a short-side direction of the anisotropic conductive film and at least a prescribed length in a long-side direction of the anisotropic conductive film.

TECHNICAL FIELD

The present invention relates to an anisotropic conductive film.

BACKGROUND ART

Anisotropic conductive films in which conductive particles are dispersedin an insulating resin binder are widely used when mounting electroniccomponents such as IC chips to substrates. There is a strong demand toincrease the capacity of an anisotropic conductive film to captureconductive particles on bumps and to be able to avoid shorting bynarrowing the pitch of bumps, which accompany the high-density mountingof electronic components of recent years.

To adapt anisotropic conductive films to this demand, various techniquesfor regularly disposing conductive particles in an array have beeninvestigated. For example, a technique of disposing conductive particleswith a single layer by laying conductive particles over a stretched filmand biaxially stretching the film (Patent Document 1), a technique ofholding conductive particles on a substrate using magnetism andtransferring the conductive particles to an adhesive film to arrange theconductive particles in a prescribed array (Patent Document 2), and thelike are known.

CITATION LIST Patent Literature

Patent Document 1: JP 5147048 B

Patent Document 2: JP 4887700 B

SUMMARY OF INVENTION Technical Problem

However, in a biaxial stretching method, it is difficult to arrangeconductive particles at prescribed positions with precision, andomissions frequently occur in the arrangement of the conductiveparticles. With a transfer method, conductive particles can be disposedwith higher precision than with a biaxial stretching method, but it isdifficult to completely eliminate the omissions in conductive particlesover the entire surface of the anisotropic conductive film.

In addition, since an anisotropic conductive film product is typicallyproduced with long dimensions of 5 m or greater, it is difficult andunrealistic to produce a film with no omissions in conductive particleswhatsoever over the entire length. For example, when a film with aomission in even one section is designated as a nonstandard defectiveproduct, the product yield decreases, and the production cost of theproduct increases. On the other hand, when omissions in conductiveparticles are widespread over a product, problems arise with theconnection stability of anisotropic conductive connections.

Therefore, an object of the present invention is to enable anisotropicconductive connections on par with those of an anisotropic conductivefilm without omissions, even with an anisotropic conductive film inwhich omissions are present in a prescribed regular disposition ofconductive particles.

Solution to Problem

The present inventors discovered that even in a case where there areomissions in a prescribed regular disposition of conductive particles,problems do not arise with anisotropic conductive connections in thefollowing cases (A) to (C).

(A) When omissions are consecutive in a prescribed regular dispositionof conductive particles, conduction failure tends to occur, and thistendency is particularly strong when omissions are consecutive in thelong-side direction of an anisotropic conductive film. However, even ina case where there are consecutive omissions in the long-side directionof an anisotropic conductive film, conduction failure is unlikely tooccur as long as the number of consecutive omissions is not greater thana prescribed number corresponding to the object of connection.

(B) When an anisotropic conductive film is used in film on glass (FOG)or the like in which the respective bump areas are relatively large, thebump width is typically at most around 200 μm. As long as there are tenor more conductive particles in a range of 200 μm in the long-sidedirection of the anisotropic conductive film, substantially no problemswith connections arise even in a case where there are omissions in theregular disposition of the conductive particles.

(C) When an anisotropic conductive film is used in chip on glass (COG)in which bumps are positioned in specific sections (for example, thereare rows of bumps at both ends in the short-side direction) and therespective bump areas are relatively small, as long as the sectionsincluding at least a prescribed number of consecutive omissions inconductive particles (that is, sections with large omissions of a levelthat would be problematic for practical use) are present along both endsin the short-side direction of the anisotropic conductive film whenaligning both ends in the short-side direction of the anisotropicconductive film and the terminal arrays of the chips, problems areunlikely to arise with connections even if there are more than aprescribed number of consecutive omissions in conductive particles inthe central portion in the short-side direction.

The present invention is conceived based on these findings and providesan anisotropic conductive film at least 5 m long having a regulardisposition region in which conductive particles are disposed regularlyin an insulating resin binder, wherein a standard region including nosections with more than a prescribed number of consecutive omissions inconductive particles is present in the regular disposition region over aprescribed width in a short-side direction of the anisotropic conductivefilm and at least a prescribed length in a long-side direction of theanisotropic conductive film.

The configuration of the anisotropic conductive film of an embodiment ofthe present invention is significant in that, even in a case where thereare omissions in a prescribed regular disposition of conductiveparticles, anisotropic conductive connections on par with those of ananisotropic conductive film without omissions can be achieved; in otherwords, the amount of conductive particles that are present is reducedwithin a range that does not diminish the characteristics of theanisotropic conductive film. Accordingly, the anisotropic conductivefilm of an embodiment of the present invention enables a reduction inthe amount of metal used for conductive particles, which not only yieldsan effect of cutting the production cost, but also contributes to aneffect of reducing the environmental burden or to the mitigation of thespecification conditions of an anisotropic conductive film product(enhancement of production yield). To achieve stable conductionproperties with the smallest number of conductive particles required foranisotropic conductive connection in this way, the regular dispositionregion and the standard region preferably match. Note that as long asthe effect of an embodiment of the present invention is notsubstantially diminished, there may also be nonstandard sections, whichare sections including at least a prescribed number of consecutiveomissions in conductive particles.

In particular, as an anisotropic conductive film in which the respectivebump areas are relatively small and the number of bumps is large, forexample, an anisotropic conductive film for chip on glass (COG), thepresent invention provides a mode having a standard region along atleast an end region in the short-side direction of the anisotropicconductive film.

In addition, as an anisotropic conductive film in which the respectivebump areas are relatively large, for example, an anisotropic conductivefilm for film on glass (FOG), the present invention provides a mode inwhich ten or more conductive particles are present in an discretionarilyselected region of 200 μm in the long-side direction over the entirewidth of the anisotropic conductive film.

The present invention also provides a method for producing ananisotropic conductive film at least 5 m long, wherein a wide basematerial of an anisotropic conductive film in which conductive particlesare disposed regularly in an insulating resin binder is cut in a lengthdirection so that no nonstandard sections including at least aprescribed number of consecutive omissions in conductive particles areincluded in a regular disposition, or so that nonstandard sections areat intended positions in a short-side direction of the film.

The present invention also provides a method for producing ananisotropic conductive film at least 5 m long, wherein nonstandardsections including at least a prescribed number of consecutive omissionsin conductive particles are removed from an anisotropic conductive filmincluding a standard disposition region in which conductive particlesare disposed regularly in an insulating resin binder, and theanisotropic conductive films after removal are connected. As long as thefilm is at least 5 m long, the film can be mounted on an anisotropicconductive connection apparatus for continuous production and can beinspected easily. That is, the burden of inspection can be reduced whensubstituted for an anisotropic conductive film used in a general-purposeanisotropic conductive connection structure.

The present invention further provides a method for producing aconnection structure, the method including establishing an anisotropicconductive connection between terminal arrays of a first electroniccomponent and a second electronic component by subjecting a firstelectronic component including a terminal array and a second electroniccomponent including a terminal array to thermocompression bonding via ananisotropic conductive film including a standard disposition region inwhich conductive particles are disposed regularly in an insulating resinbinder,

wherein an anisotropic conductive film in which a standard regionincluding no sections with more than a prescribed number of consecutiveomissions in conductive particles is formed in the standard dispositionregion over a prescribed width in a short-side direction of theanisotropic conductive film and a prescribed length in a long-sidedirection of the anisotropic conductive film is used as an anisotropicconductive film; and

the standard region is aligned with the terminal arrays of theelectronic components.

In this method, when the first electronic component and the secondelectronic component respectively have a plurality of terminal arraysand the standard regions are formed in an array on the anisotropicconductive film, the regions between adjacent standard regions arepreferably aligned with the regions between the respective terminalarrays.

Advantageous Effects of Invention

With the production method for an anisotropic conductive film accordingto the present invention, an anisotropic conductive film can be producedby extracting regions with no problems from a practical stand point froman anisotropic conductive film that has been assessed to be defectivedue to omissions in conductive particles. In addition, with the methodfor producing a connection structure according to the present invention,even in a case where the anisotropic conductive film used in theproduction of a connection structure includes sections assessed to beproblematic from the perspective of omissions in conductive particles,when a region including no sections with more than a prescribed numberof consecutive omissions in conductive particle is extended over aprescribed width in the short-side direction of the anisotropicconductive film and a prescribed length in the long-side direction ofthe anisotropic conductive film, the standard region is aligned with theterminal arrays of the electronic components. Accordingly, theproduction yield of the anisotropic conductive film can be enhancedwithout diminishing the reliability of anisotropic conductiveconnections.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view for explaining the disposition of conductiveparticles in an anisotropic conductive film 1A of examples.

FIG. 2 is a plan view for explaining the disposition of conductiveparticles in an anisotropic conductive film 1B of the examples.

FIG. 3 is a plan view for explaining the disposition of conductiveparticles in an anisotropic conductive film 1C of the examples.

FIG. 4 is a plan view illustrating the positions of sections with anonstandard disposition of conductive particles in an anisotropicconductive film for COG.

FIG. 5 is a cross-sectional view of an anisotropic conductive film 1 aof the examples.

FIG. 6 is a cross-sectional view of an anisotropic conductive film 1 bof the examples.

FIG. 7 is a cross-sectional view of an anisotropic conductive film 1 cof the examples.

FIG. 8 is a cross-sectional view of an anisotropic conductive film 1 dof the examples.

FIG. 9 is a cross-sectional view of an anisotropic conductive film 1 eof the examples.

FIG. 10 is a schematic diagram illustrating the bump arrangement of anIC for evaluation.

DESCRIPTION OF EMBODIMENTS

The present invention will be described in detail hereinafter withreference to the drawings. Note that in the drawings, the same referencecharacters are used to indicate components that are the same orequivalent.

Anisotropic Conductive Film Overall Configuration of AnisotropicConductive Film

The anisotropic conductive film of an embodiment of the presentinvention includes a region in which conductive particles are disposedregularly in an insulating resin binder (regular disposition region),and the conductive particles are preferably distanced from one anotherand disposed regularly (in a lattice form, for example) in a plan view.Here, one regular disposition region may extend over the entire surfaceof the anisotropic conductive film, or a plurality of groups ofconductive particles may be respectively disposed at a distance from oneanother as regular disposition regions over the entire surface.

Since the anisotropic conductive film of an embodiment of the presentinvention has a regular disposition region, omissions in conductiveparticles in a regular disposition of conductive particles can be testedand understood accurately. The anisotropic conductive film of anembodiment of the present invention is one in which a standard regionincluding no sections with more than a prescribed number of consecutiveomissions in conductive particles is present in such a regulardisposition region over a prescribed width in a short-side direction ofthe anisotropic conductive film and at least a prescribed length in along-side direction of the anisotropic conductive film. Note that when aplurality of groups of conductive particles are respectively disposed ata distance from one another as regular disposition regions over theentire surface of an anisotropic conductive film, a standard region ispresent in each of the regular disposition regions over a prescribedwidth in the short-side direction of the anisotropic conductive film andat least a prescribed length in the long-side direction of theanisotropic conductive film.

Here, with regard to the standard region, the short-side direction ofthe anisotropic conductive film serves as the long-side direction of aterminal in a typical anisotropic conductive connection structure. Thus,the capacity to capture conductive particles extending in the short-sidedirection of the anisotropic conductive film with the terminal isenhanced, and the anisotropic conductive connection conditions can bemitigated relatively easily. Accordingly, when the anisotropicconductive film is completely pressed into a connection tool in theshort-side direction to contribute to an anisotropic conductiveconnection, the pressing width conditions in the short-side direction ofthe anisotropic conductive film can also be mitigated. Specifically, theupper limit of the “prescribed width” in the short-side direction of theanisotropic conductive film is preferably not greater than 95% and morepreferably not greater than 90% of the short-side direction of theanisotropic conductive film, and the lower limit is preferably not lessthan 10% and more preferably not less than 20% of the short-sidedirection of the anisotropic conductive film. In addition, the positionof the “prescribed width” in the short-side direction of the anisotropicconductive film is preferably a position other than the central portionin the short-side direction of the anisotropic conductive film, that is,at the ends (both ends) so that the film can be easily applied to ananisotropic conductive connection of an IC chip such as a typical COG oran anisotropic conductive connection with a similar terminal layout. Thewidths of the respective standard regions at both ends may be the sameas or different than one another. This is to accommodate the requiredterminal layout.

On the other hand, with regard to the standard region, “at least aprescribed length” in the long-side direction of the anisotropicconductive film (that is, the short-side direction of a terminal in atypical anisotropic conductive connection structure) may be not lessthan 5 mm, preferably not less than 10 mm, and more preferably not lessthan 20 mm (equivalent to 0.4% when the length of the anisotropicconductive film is 5 m) on the basis of an anisotropic conductiveconnection structure (for example, a small site mounting body withdimensions of 10 mm squared such as a camera module). In addition, inthe case of a large anisotropic conductive connection structure (forexample, a large display of 80 or more inches), the regular dispositionregion may be 2000 mm or greater.

Note that with regard to the standard region, the upper limit of “atleast a prescribed length” in the long-side direction of the anisotropicconductive film is preferably longer in that the quality of theanisotropic conductive film itself is enhanced. Accordingly, althoughthe upper limit of “at least a prescribed length” is not particularlylimited, from the perspective of performing imaging examinations whenmanaging the quality of the anisotropic conductive film, limiting thevalue to a certain length also facilitates quality-related informationmanagement. For example, by dividing the film at a certain length,comparisons of data for each section of that length can be performedeasily. In addition, there is also the advantage that the volume ofimage data can simply be small. An example of the upper limit of “atleast a prescribed length” is not greater than 1000 m, and when theupper limit is preferably not greater than 500 m, more preferably notgreater than 350 m, and even more preferably not greater than 50 m,image data for tests can be processed or managed easily.

Note that it is preferable for the standard region to be equal and inalignment with the regular disposition region from the perspective ofstable connections. Note that as long as the effect of the presentinvention is not substantially diminished, there may also be sections(nonstandard sections) including at least a prescribed number ofconsecutive omissions in conductive particles in the regular dispositionregion. Also note that a blank region in which no conductive particlesare present or a random disposition region in which conductive particlesare disposed at random may also be present outside the regulardisposition region of the anisotropic conductive film.

In addition, to stabilize the productivity of a connection structureusing an anisotropic conductive connection, the length of theanisotropic conductive film of an embodiment of the present invention ispreferably not less than 5 m, more preferably not less than 10 m, andeven more preferably not less than 50 m. On the other hand, when thefilm length is too large, the effort is required to set the film in theapparatus or to transport the film, or the cost of modifying theapparatus becomes large, and thus the length is preferably not greaterthan 5000 m, more preferably not greater than 1000 m, and even morepreferably not greater than 500 m. In addition, the film width is notparticularly limited but is, for example, from 0.5 to 5 mm.

Since the anisotropic conductive film has a large length relative to thewidth, the film is preferably a wound body which is wound around a reel.The wound body may be formed by connecting a plurality of anisotropicconductive films to one another. A connection tape may be used toconnect the anisotropic conductive films. The thickness of theconnection tape is not particularly limited, but when the tape is toothick, the tape may have an adverse effect on the protrusion or blockingof the resin. Thus, the thickness is preferably from 10 to 40 μm.

Disposition of Conductive Particles

An example of a regular disposition of conductive particles is a squarelattice arrangement, as in the anisotropic conductive film 1Aillustrated in FIG. 1. Other examples of a regular disposition ofconductive particles include lattice arrangements such as a rectangularlattice, a rhombic lattice, or a hexagonal lattice. Rows of particles inwhich conductive particles are arranged linearly at a prescribed spacingmay be arranged at a prescribed spacing. In addition, as in theanisotropic conductive film 1B illustrated in FIG. 2, conductiveparticles 2 may account for a plurality of the vertices of a regularpolygon (in this example, a regular hexagon) when regular polygons arejuxtaposed without spacing therebetween, and the disposition of theconductive particles may be conceptualized as trapezoidal repeatingunits 5 including conductive particles 2 a, 2 b, 2 c, and 2 d. Note thata trapezoidal repeating unit is one example of a regular disposition ofconductive particles, and the units may be distanced from one another,or a collection of a plurality of repeating units may form isolatedregular disposition regions of conductive particles. Here, the repeatingunits 5 are repeating units of the disposition of conductive particlesformed by successively connecting the centers of the closest conductiveparticles 2, and the repeating units 5 extend all over the anisotropicconductive film by means of repetition with prescribed regularity. Thedisposition shape of the conductive particles in the repeating units 5themselves is not particularly limited, but when the conductiveparticles 2 covers a portion of the regular polygon in a repeating unit5, the disposition of the conductive particles is easy to understand.Thus, the presence or absence of omissions in conductive particles withrespect to a prescribed disposition can be easily assessed. Note thatwhen the disposition of the conductive particles is easily understood,the respective operations become easy at the time of production of ananisotropic conductive film or in product tests such as indentationtests after an electronic component is connected using the anisotropicconductive film, which makes it possible to reduce the operation timeand to reduce the workload.

The lattice axis or arrangement axis of the arrangement of theconductive particles 2 may be parallel to the long-side direction of theanisotropic conductive film or may intersect with the long-sidedirection of the anisotropic conductive film and can be determined inaccordance with the terminal width, terminal pitch, or the like of theterminal to be connected. For example, in the case of an anisotropicconductive film for a fine pitch, as illustrated in FIG. 1, the latticeaxis L1 of the conductive particles 2 intersects obliquely with thelong-side direction of the anisotropic conductive film 1A, and the angleθ formed by the long-side direction (short-side direction of the film)of a terminal 10 to be connected with the anisotropic conductive film 1Aand the lattice axis L1 is from 6° to 84° and is preferably from 11° to74°.

Conductive Particles

Any conductive particles used in a known anisotropic conductive film maybe appropriately selected and used as the conductive particles 2.Examples of the conductive particles include metal particles such asnickel, copper, silver, gold, and palladium and metal-coated resinparticles, where the surface of resin particles such as polyamide andpolybenzoguanamine is coated with a metal such as nickel. The diameterof the disposed conductive particles is preferably not less than 1 μmand not greater than 30 μm, more preferably not less than 1 μm and notgreater than 10 μm, and even more preferably not less than 2 μm and notgreater than 6 μm.

The average particle diameter of the conductive particles 2 can bemeasured by using an image-type or laser-type particle size distributionmeter. The anisotropic conductive film may be observed in a plan view tomeasure and determine the particle diameter. In this case, preferably atleast 200 particles, more preferably at least 500 particles, and evenmore preferably at least 1000 particles are measured.

The surfaces of the conductive particles 2 are preferably coated byinsulating coating, insulating particle treatment, or the like. Acoating which is not easily peeled from the surfaces of the conductiveparticles 2 and does not cause problems with anisotropic conductiveconnection is selected as such a coating. In addition, protrusions maybe formed on all or a portion of the surfaces of the conductiveparticles 2. The height of the protrusions is not greater than 20% andpreferably not greater than 10% of the conductive particle diameter.

Shortest Distance Between Conductive Particles

The shortest distance between conductive particles is preferably notless than 0.5 times the average particle diameter of the conductiveparticles. When this distance is too small, shorting becomes more likelyto occur due to contact between conductive particles. The upper limit ofthe distance between adjacent conductive particles can be determined inaccordance with the bump shape or the bump pitch. As one example, whenten or more conductive particles are to be captured, the distance may beless than 50 times and is preferably less than 40 times the averageparticle diameter. The distance is more preferably less than 30 timesthe average particle diameter.

Number Density of Conductive Particles

From the perspective of suppressing the production cost of theanisotropic conductive film, the number density of the conductiveparticles is preferably not greater than 50000 particles/mm², morepreferably not greater than 35000 particles/mm², and even morepreferably not greater than 30000 particles/mm². On the other hand,since poor conduction due to the insufficient capture of conductiveparticles by the terminals is a concern when the number density of theconductive particles is too small, the number density may be not lessthan 30 particles/mm² and is preferably not less than 300 particles/mm²,more preferably not less than 500 particles/mm², and even morepreferably not less than 800 particles/mm².

Insulating Resin Binder

As the insulating resin binder 3, a thermo-polymerizable composition, aphotopolymerizable composition, a polymerizable composition using bothlight and heat, or the like that is used as an insulating resin binderin a known anisotropic conductive film may be appropriately selected andused. Of these, examples of thermo-polymerizable compositions includethermal radical polymerizable resin compositions containing an acrylatecompound and a thermal radical polymerization initiator, thermalcationic polymerizable resin compositions containing an epoxy compoundand a thermal cationic polymerization initiator, and thermal anionicpolymerizable resin compositions containing an epoxy compound and athermal anionic polymerization initiator. Examples of photopolymerizablecompositions include photoradical polymerizable resin compositions orthe like containing an acrylate compound and a photoradicalpolymerization initiator. A plurality of types of polymerizablecompositions may be used in combination as long as no particularproblems arise. An example of combined use is the combined use of athermal cationic polymerizable composition and a thermal radialpolymerizable composition.

Here, a plurality of types of photopolymerization initiators which reactwith light of different wavelengths may be included. As a result,different wavelengths may be used for the photocuring of a resin formingthe insulating resin layer at the time of the production of theanisotropic conductive film and the photocuring of a resin for bondingelectronic components to one another at the time of anisotropicconductive connection.

When the insulating resin binder 3 is formed using a photopolymerizablecomposition, all or a portion of the photopolymerizable compoundcontained in the insulating resin binder 3 may be photocured by means ofphotocuring at the time of the production of the anisotropic conductivefilm. As a result of this photocuring, the disposition of the conductiveparticles 2 in the insulating resin binder 3 is maintained orstabilized, which yields prospects for the suppression of shorting andthe enhancement of capturing. In addition, by adjusting the conditionsof this photocuring, the viscosity of the insulating resin layer in theproduction process of the anisotropic conductive film can be adjusted.

The compounded amount of the photopolymerizable compound in theinsulating resin binder 3 is preferably not greater than 30 mass %, morepreferably not greater than 10 mass %, and even more preferably lessthan 2 mass %. This is because when the amount of the photopolymerizablecompound is too large, the thrust required for pressing at the time ofanisotropic conductive connection increases.

On the other hand, although the thermo-polymerizable compositioncontains a thermo-polymerizable compound and a thermal polymerizationinitiator, a compound which also functions as a photopolymerizablecompound may also be used as this thermo-polymerizable compound. Inaddition, the thermo-polymerizable composition may also contain aphotopolymerizable compound separately from the thermo-polymerizablecompound as well as a photopolymerization initiator. The compositionpreferably contains a photopolymerizable compound and aphotopolymerization initiator separately from the thermo-polymerizablecompound. For example, a thermal cationic polymerization initiator maybe used as a thermal polymerization initiator, an epoxy resin may beused as a thermo-polymerizable compound, a photoradical polymerizationinitiator may be used as a photopolymerization initiator, and anacrylate compound may be used as a photopolymerizable compound. Theinsulating binder 3 may also contain a cured product of thesepolymerizable compositions.

The acrylate compound used as a thermo or photopolymerizable compoundmay be a known thermally polymerizable (meth)acrylate monomer. Examplesthereof include monofunctional (meth)acrylate-based monomers andpolyfunctional, that is, two or more functional, (meth)acrylate-basedmonomers.

In addition, an epoxy compound used as a polymerizable compound forms athree-dimensional mesh structure to provide good heat resistance andadhesiveness, and a solid epoxy resin and a liquid epoxy resin arepreferably used in combination. Here, a solid epoxy resin refers to anepoxy resin which is a solid at room temperature. In addition, a liquidepoxy resin refers to an epoxy resin which is a liquid at roomtemperature. Room temperature refers to the temperature range from 5 to35° C. prescribed by JIS Z 8703. In an embodiment of the presentinvention, two or more types of epoxy compounds may be used incombination. An oxetane compound may be used in addition to the epoxycompound.

The solid epoxy resin is not particularly limited as long as it iscompatible with the liquid epoxy resin and is a solid at roomtemperature, and examples thereof include bisphenol A epoxy resins,bisphenol F epoxy resins, polyfunctional epoxy resins, dicyclopentadieneepoxy resins, novolac phenol epoxy resins, biphenol epoxy resins, andnaphthalene epoxy resins. One type of these may be used alone, or two ormore types may be used in combination. Of these, it is preferable to usea bisphenol A epoxy resin.

The liquid epoxy resin is not particularly limited as long as it is aliquid at room temperature, and examples thereof include bisphenol Aepoxy resins, bisphenol F epoxy resins, novolac phenol epoxy resins andnaphthalene epoxy resins. One type of these may be used alone, or two ormore types may be used in combination. In particular, it is preferableto use a bisphenol A epoxy resin from the perspective of tackiness ofthe film, flexibility or the like.

Of the thermal polymerization initiator, examples of thermal radicalpolymerization initiators may include organic peroxides and azocompounds. In particular, organic peroxides may be preferred becausethey do not produce nitrogen, which can induce bubbles.

The amount of the thermal radical polymerization initiator to be usedpreferably ranges from 2 to 60 parts by mass, and more preferably from 5to 40 parts by mass, per 100 parts by mass of a (meth)acrylate compound.When the amount is too small, insufficient curing will occur. When theamount is too large, the product life will decrease.

The thermal cationic polymerization initiator may be a known thermalcationic polymerization initiator for epoxy compounds. Examples of theinitiator include iodonium salts, sulfonium salts, phosphonium salts,and ferrocenes, which generate acid via heat. In particular, aromaticsulfonium salts, which exhibit good temperature latency, may bepreferred.

The amount of the thermal cationic polymerization initiator to be usedpreferably ranges from 2 to 60 parts by mass, and more preferably from 5to 40 parts by mass, per 100 parts by mass of an epoxy compound. Whenthe amount is too small, insufficient curing tends to occur. When theamount is too large, the product life tends to decrease.

A publicly known curing agent that is ordinarily used can be used as theanionic polymerization initiator. Examples include organic aciddihydrazide, dicyandiamide, amine compounds, polyamide amine compounds,cyanate ester compounds, phenol resins, acid anhydride, carboxylic acid,tertiary amine compounds, imidazole, Lewis acid, Bronsted acid salts,polymercaptan-based curing agents, urea resins, melamine resins,isocyanate compounds, and block isocyanate compounds. One type of thesemay be used alone, or two or more types may be used in combination. Ofthese, it is preferable to use a microcapsule-type latent curing agentformed by using an imidazole-modified substance as a core and coveringthe surface thereof with polyurethane.

The thermo-polymerizable composition preferably contains a film formingresin. The film-forming resin corresponds to a high-molecular-weightresin having an average molecular weight of not less than 10000, forexample, and an average molecular weight of from approximately 10000 toapproximately 80000 is preferable from the perspective of filmformability. Examples of film-forming resins include various resins suchas phenoxy resins, polyester resins, polyurethane resins, polyesterurethane resins, acrylic resins, polyimide resins, and butyral resins.These may be used alone, or two or more types may be used incombination. Of these, a phenoxy resin is may be suitably used from thestandpoints of film formation state, connection reliability, and thelike.

The thermo-polymerizable composition may also contain an insulatingfiller to adjust the melt viscosity. Examples of this include silicapowders and alumina powders. The size of the insulating filler ispreferably from 20 to 1000 nm, and the compounded amount is preferablyfrom 5 to 50 parts by mass per 100 parts by mass of thethermo-polymerizable compound (photopolymerizable compound) such as anepoxy compound. Further, thermo-polymerizable composition may alsocontain fillers, softeners, promoters, antioxidants, colorants (pigmentsand dyes), organic solvents, ion scavengers, and the like which differfrom the insulating filler described above.

In addition, stress relaxation agents, silane coupling agents, inorganicfillers, or the like may also be compounded as necessary. Examples ofstress relaxation agents include hydrogenated styrene-butadiene blockcopolymers and hydrogenated styrene-isoprene block copolymers. Examplesof silane coupling agents include epoxy-based, methacryloxy-based,amino-based, vinyl-based, mercapto-sulfoxide-based, and ureide-basedsilane coupling agents. Examples of inorganic fillers include silica,talc, titanium oxide, calcium carbonate, and magnesium oxide.

Note that the insulating resin binder 3 may be formed by depositing acoating composition containing the resin described above to form a layerby a coating method and drying or further curing, or otherwise byforming a film using a known technique in advance. The insulating resinbinder 3 may be obtained by laminating a resin layer as necessary. Inaddition, the insulating resin binder 3 is preferably formed on arelease film such as a polyethylene terephthalate film that has beenrelease-treated.

Viscosity of Insulating Resin Binder

The minimum melt viscosity of the insulating resin binder 3 can bedetermined appropriately in accordance with the production method or thelike of the anisotropic conductive film. For example, when a method ofholding the conductive particles at a prescribed disposition on thesurface of the insulating resin binder and pressing the conductiveparticles into the insulating resin binder is used as the productionmethod of the anisotropic conductive film, the minimum melt viscosity ofthe insulating resin binder 3 is preferably not less than 1100 Pa·s fromthe perspective of film formability. In particular, from the perspectiveof enabling film formation at 40 to 80° C., the 60° viscosity of theinsulating resin binder 3 is preferably from 3000 to 20000 Pa·s. Inaddition, as described below, from the perspective of formingconcavities 3 b around the exposed portions of the conductive particles2 pressed into the insulating resin binder 3, as illustrated in FIG. 5or 6, or from the perspective of forming concavities 3 c directly abovethe conductive particles 2 pressed into the insulating resin binder 3,as illustrated in FIG. 7, the minimum melt viscosity of the insulatingresin binder 3 may be not less than 1500 Pa·s and is preferably not lessthan 2000 Pa·s, more preferably from 3000 to 15000 Pa·s, and even morepreferably from 3000 to 10000 Pa·s. The minimum melt viscosity may bedetermined in the following manner, for example. A rotary rheometer(available from TA Instruments) is used, a rate of temperature increaseof 10° C./min and a measurement pressure of 5 g are maintained to beconstant, and a measurement plate of 8 mm in diameter is used. Inaddition, when performing the step of pressing the conductive particles2 into the insulating resin binder 3 at 40 to 80° C., the viscosity ofthe insulating resin binder 3 at 60° C. is preferably from 3000 to 20000Pa·s from the perspective of the formation of the concavity 3 b or 3 c,as described above. This measurement is made with the same measurementmethod as in the case of the minimum melt viscosity, and the viscositycan be determined by extracting the value at a temperature of 60° C.

By setting the viscosity of the resin forming the insulating resinbinder 3 to a high viscosity as described above, the conductiveparticles 2 inside the anisotropic conductive film can be prevented frombeing carried away by the flow of the melted insulating resin binder 3when the conductive particles 2 are interposed between objects to beconnected such as opposing electronic components and pressurized whileheating at the time of the use of the anisotropic conductive film. Inaddition, when the amount of resin around or directly above theconductive particles is substantially zero or is reduced in comparisonto the surrounding area thereof, as in the case of the concavity 3 b or3 c, the pressing force applied to the conductive particles from theconnecting tool is easily transmitted. Thus, the conductive particlescan be interposed effectively between the terminals, and an improvementin conduction properties or an improvement in the capacity to captureconductive particles can be anticipated.

Thickness of Insulating Resin Binder

The thickness La of the insulating resin binder 3 is preferably not lessthan 1 μm and not greater than 60 μm, more preferably not less than 1 μmand not greater than 30 μm, and even more preferably not less than 2 μmand not greater than 15 μm. In addition, the thickness La of theinsulating resin binder 3 is preferably such that the ratio (La/D) isfrom 0.6 to 10 in the relationship between the thickness La and theaverage particle diameter D of the conductive particles 2. When thethickness La of the insulating resin binder 3 is too large, theconductive particles tend to be displaced at the time of anisotropicconductive connection, and the capacity to capture conductive particlesat the terminals is diminished. This trend is marked when La/D exceeds10. Therefore, La/D is more preferably not greater than 8 and even morepreferably not greater than 6. Conversely, when the thickness La of theinsulating resin binder 3 is too small and La/D is less than 0.6, itbecomes difficult to keep the conductive particles in a prescribedparticle dispersion state or a prescribed arrangement with theinsulating resin binder 3. In particular, when the terminal to beconnected is a high-density COG, the ratio (La/D) of the layer thicknessLa of the insulating resin binder 3 to the particle diameter D of theconductive particles 2 is preferably from 0.8 to 2.

Mode in Which Conductive Particles are Embedded in the Insulating ResinBinder

The embedded state of conductive particles 2 in the insulating resinbinder 3 is not particularly limited, but when anisotropic conductiveconnection is performed by sandwiching the anisotropic conductive filmbetween opposing parts and applying pressure while heating, theconductive particles 2 are partially exposed from the insulating resinbinder 3 to form concavities 3 b around the exposed portions of theconductive particles 2 with respect to the tangential plane 3 p of thesurface 3 a of the insulating resin binder in the central portionbetween adjacent conductive particles 2, as illustrated in FIGS. 5 and6, or concavities 3 c are formed in the insulating resin binder portiondirectly above the conductive particles 2 pressed into the insulatingresin binder 3 with respect to the same tangential plane 3 p as thatdescribed above, and waves are preferably present in the surface of theinsulating resin binder 3 directly above the conductive particles 2, asillustrated in FIG. 7. With respect to the flattening of the conductiveparticles 2 which occurs when the conductive particles 2 are interposedbetween the electrodes of opposing electronic components and arepressurized while heating, the presence of the concavities 3 billustrated in FIG. 5 leads to a reduction in the resistance applied tothe conductive particles 2 from the insulating resin binder 3 incomparison to cases in which no concavities 3 b are present. Therefore,the conductive particles 2 are more easily interposed between theopposing electrodes, and the conduction performance also improves. Inaddition, of the resins constituting the insulating resin binder 3, whenconcavities 3 c (FIG. 7) are formed in the surface of the resin directlyabove the conductive particles 2, the pressure at the time ofpressurization under heat is more easily concentrated on the conductiveparticles 2 than when no concavities 3 c are present, and the conductiveparticles 2 are more easily interposed between the electrodes, whichenhances the conduction performance.

From the perspective of more easily achieving the effect of theconcavities 3 b and 3 c described above, the ratio (Le/D) of the maximumdepth Le of the concavities 3 b (FIGS. 5 and 6) around the exposedportions of the conductive particles 2 to the average particle diameterD of the conductive particles 2 is preferably less than 50%, morepreferably less than 30%, and even more preferably from 20 to 25%. Theratio (Ld/D) of the maximum diameter Ld of the concavities 3 b (FIGS. 5and 6) around the exposed portions of the conductive particles 2 to theaverage particle diameter D of the conductive particles 2 is preferablynot greater than 150% and more preferably from 100 to 130%. The ratio(Lf/D) of the maximum depth Lf of the concavities 3 c (FIG. 7) in theresin directly above the conductive particles 2 to the average particlediameter D of the conductive particles 2 is greater than 0, preferablyless than 10%, and more preferably not greater than 5%.

The diameter Lc of the exposed portion of the conductive particles 2 maybe not greater than the average particle diameter D of the conductiveparticles 2, and conductive particles 2 may be exposed at one point atthe apical part 2 t of the conductive particle 2, or the conductiveparticles 2 may be completely embedded in the insulating resin binder 3so that the diameter Lc is zero. From the perspective of the ease ofadjusting the positions of the conductive particles when the conductiveparticles are embedded in the insulating resin layer by pressing theconductive particles into the insulating resin layer, the diameter Lc ispreferably not greater than 15%.

Positions of Conductive Particles in Thickness Direction of InsulatingResin Binder

From the perspective of more easily achieving the effect of theconcavities 3 b described above, the ratio (Lb/D) (called the “embeddingrate” hereafter) of the distance of the deepest part of the conductiveparticles 2 from the tangential plane 3 p (called the “embedded amount”hereafter) to the average particle diameter D of the conductiveparticles 2 is preferably not less than 60% and not greater than 105%.

Insulating Adhesive Layer

In the anisotropic conductive film of an embodiment of the presentinvention, an insulating adhesive layer 4 may be laminated on theinsulating resin binder 3 in which the conductive particles 2 aredisposed.

When the concavities 3 b described above are formed in the insulatingresin binder 3, the insulating adhesive layer 4 may be laminated on thesurface where the concavities 3 b are formed in the insulating resinbinder 3, as in the anisotropic conductive film 1 d illustrated in FIG.8, or may be laminated on the surface on the opposite side as thesurface where the concavities 3 b are formed, as in the anisotropicconductive film 1 e illustrated in FIG. 9. This is also the same forcases in which the concavities 3 c are formed in the insulating resinbinder 3. As a result of the lamination of the insulating adhesive layer4, the spaces formed by the electrodes or bumps of the electroniccomponent can be filled when the electronic component is anisotropicallyconductively connected using the anisotropic conductive film, whichmakes it possible to enhance the adhesiveness.

Note that when the insulating adhesive layer 4 is laminated on theinsulating resin binder 3, the insulating adhesive layer 4 is preferablyon the side of an electronic component such as an IC chip which ispressed with a tool (in other words, the insulating resin binder 3 is onthe side of an electronic component such as a substrate mounted on astage), regardless of whether the insulating adhesive layer 4 is locatedon the surface where the concavities 3 b and 3 c are formed. As aresult, the unintended movement of the conductive particles can beavoided, and the capturing performance can be enhanced.

The insulating adhesive layer 4 may be the same as a layer used as aninsulating adhesive layer in a known anisotropic conductive film, andthe viscosity may be adjusted to a lower level using the same resin asthat of the insulating resin binder 3 described above. A greaterdifference between the minimum melt viscosities of the insulatingadhesive layer 4 and the insulating resin binder 3 makes it easier forthe space formed by the electrodes or bumps of the electronic componentto be filled with the insulating adhesive layer 4, which makes itpossible to anticipate an effect of enhancing the adhesiveness betweenelectronic components. In addition, when this difference is greater, theamount of movement of the resin forming the insulating resin binder 3becomes relatively small at the time of anisotropic conductiveconnection, and thereby the capacity to capture conductive particles atthe terminals is more easily enhanced. From a practical standpoint, theminimum melt viscosity ratio of the insulating adhesive layer 4 and theinsulating resin binder 3 is preferably not less than 2, more preferablynot less than 5, and even more preferably not less than 8. On the otherhand, when this ratio is too large, the protrusion or blocking of theresin may occur when a long anisotropic conductive film is formed into awound body, and therefore the ratio is preferably not greater than 15from a practical standpoint. More specifically, the preferable minimummelt viscosity of the insulating adhesive layer 4 satisfies the ratiodescribed above and is not greater than 3000 Pa·s, more preferably notgreater than 2000 Pa·s, and particularly preferably from 100 to 2000Pa·s.

As a method of forming the insulating adhesive layer 4, the layer may beformed by depositing a coating composition containing the same resin asthe resin used to form the insulating resin binder 3 with a coatingmethod and drying or further curing, or by forming a film with a knowntechnique in advance.

The thickness of the insulating adhesive layer 4 is not particularlylimited but is preferably from 4 to 20 μm. Alternatively, the thicknessmay be from 1 to 8 times the conductive particle diameter.

In addition, the minimum melt viscosity of the entire laminatedanisotropic conductive film combining the insulating resin binder 3 andthe insulating adhesive layer 4 depends also on the ratio of thethickness of the insulating resin binder 3 to the thickness of theinsulating adhesive layer 4, but the minimum melt viscosity may be notgreater than 8000 Pa·s from a practical standpoint, and to facilitatethe filling of the spaces between bumps, the minimum melt viscosity maybe from 200 to 7000 Pa·s and is preferably from 200 to 4000 Pa·s.

Third Insulating Resin Layer

A third insulating resin layer may be provided on the opposite side soas to sandwich the insulating adhesive layer 4 and the insulating resinbinder 3. For example, the third insulating resin layer may be made tofunction as a tack layer. As in the case of the insulating adhesivelayer 4, the third insulating resin layer may also be provided to fillthe spaces formed by the electrodes or bumps of the electroniccomponent.

The resin composition, viscosity, and thickness of the third insulatingresin layer may be the same as or different than those of the insulatingadhesive layer 4. The minimum melt viscosity of the anisotropicconductive film combining the insulating resin binder 3, the insulatingadhesive layer 4, and the third insulating resin layer is notparticularly limited but may be not greater than 8000 Pa·s, from 200 to7000 Pa·s, or from 200 to 4000 Pa·s.

Further, an insulating filler such as silica fine particles, alumina,and aluminum hydroxide may be added not only to the insulating resinbinder 3, but also to the insulating adhesive layer 4 as necessary. Thecompounded amount of the insulating filler is preferably not less than 3parts by mass and not greater than 40 parts by mass per 100 parts bymass of resin included in the layers. Thereby, even when the anisotropicconductive film is melted during anisotropic conductive connection, itis possible to prevent the conductive particles from movingunnecessarily due to the melted resin.

Method for Producing Anisotropic Conductive Film Summary of ProductionMethod

In an embodiment of the present invention, a wide base material of ananisotropic conductive film in which conductive particles are disposedregularly in an insulating binder is first acquired or manufactured, andomissions in the regular disposition of the conductive particles in thebase material of the anisotropic conductive film are then investigated.To ensure that nonstandard sections including more than a prescribednumber of consecutive omissions in conductive particles with respect tothe regular disposition are not used as regions responsible forconnections, the wide base material is cut into an anisotropicconductive film of a prescribed width to remove regions includingnonstandard sections (first aspect). Alternatively, a wide base materialis cut in the length direction with a prescribed width so thatnonstandard sections are at intended positions in the short-sidedirection of the film (second aspect). In addition, an anisotropicconductive film at least 5 m long may be produced by connecting theanisotropic conductive films after the nonstandard sections are removedin the first aspect (that is, the remaining anisotropic conductive filmor separate anisotropic conductive films after the nonstandard sectionsare removed).

Here, the method for producing the initial anisotropic conductive filmprior to removing the regions described above is not particularlylimited. For example, the method may entail producing an anisotropicconductive film is a method of producing a transfer mold for disposingconductive particles in a prescribed arrangement, filling the concaveportions of the transfer mold with conductive particles, covering thetransfer mold with an insulating resin binder 3 formed on a release filmand applying pressure, and pressing the conductive particles into theinsulating resin binder 3 to transfer the conductive particles to theinsulating resin binder 3. Alternatively, an insulating adhesive layer 4may be further laminated on the conductive particles 2. Thus, theanisotropic conductive film can be obtained.

In addition, an anisotropic conductive film may be produced by fillingthe concave portions of a transfer mold with conductive particles,covering the transfer mold with an insulating resin binder, transferringthe conductive particles to the surface of the insulating resin binderfrom the transfer mold, and pressing the conductive particles on theinsulating resin binder into the insulating resin binder. The amount ofconductive particles that are embedded (Lb) can be adjusted by thepressing force, the temperature, or the like at the time of pressing. Inaddition, the shape and depth of the concavities 3 b and 3 c can beadjusted by the viscosity of the insulating resin binder, the pressingrate, the temperature, and the like at the time of pressing. Forexample, when producing an anisotropic conductive film 1 a including theconcavity 3 b illustrated in FIG. 5 or producing an anisotropicconductive film 1 c including the concavity 3 c illustrated in FIG. 7 onthe surface of an insulating resin binder, in accordance with the shapeor depth of the concavity, the lower limit of the viscosity of theinsulating resin binder at 60° C. is preferably not less than 3000 Pa·s,more preferably not less than 4000 Pa·s, and even more preferably notless than 4500 Pa·s, and the upper limit is preferably not greater than20000 Pa·s, more preferably not greater than 15000 Pa·s, and even morepreferably not greater than 10000 Pa·s. In addition, the temperature atthe time of such pressing is from 40 to 80° C. and more preferably from50 to 60° C.

Note that the transfer mold that is used may be, in addition to a moldin which the concave portions are filled with conductive particles, amold in which a slightly adhesive agent is applied to the upper surfacesof convex portions so that the conductive particles adhere to the uppersurfaces.

These transfer molds may be produced by using a known technique such asphotolithography or printing.

In addition, the method used to dispose the conductive particles in aprescribed arrangement may be a method using a biaxially stretched filminstead of a method using a transfer mold.

Handling Omission Regions

In the first mode of the method for producing an anisotropic conductivefilm according to an embodiment of the present invention, in either ananisotropic conductive film used for a connection structure in which therespective bump areas are relatively small (for example, a structuresuch as COG in which the terminal arrays to be connected are spacedapart from one another) or an anisotropic conductive film used for aconnection structure in which the respective bump areas are relativelylarge (for example, a structure such as FOG in which the long side ofthe effective area to be connected is the same as the film width, andthe terminal arrays are not spaced apart from one another), nonstandardsections including a prescribed number of consecutive sections withomissions in conductive particles are removed from the region in whichconductive particles are disposed regularly (regular disposition region)in a film in which conductive particles are disposed regularly in a planview, preferably a film in which conductive particles are distanced fromone another and disposed regularly in a plan view. In other words,regions in which the sections of omissions are merely interspersed to adegree that does not cause problems with conduction stability afterconnection are not subject to removal. This degree that does not causeproblems differs depending on the object of connection, but when ananisotropic conductive film is used for FOG, for example, problems areunlikely to arise in the conduction stability even in a case where thereare from 1 to 20 or, in some cases, from 1 to 209 consecutive omissionsin conductive particles. Here, the number 209, which is the number ofconsecutive omissions in conductive particles, has the meaning describednext. Specifically, when attempting to dispose conductive particles in a15×15 square lattice under the anisotropic conductive connectionconditions (connection area: 0.4 μm²) of a FOG, in which the connectionarea is typically large with an anisotropic conductive film width of 2mm and a connected terminal width of 200 μm, there are ideally 225conductive particles present in a connection area of 0.4 μm², but thismeans that even in a case where 209 conductive particles are missing, 16conductive particles would be present in the terminal inner region asthe minimum number of particles captured in a connection area of 0.4μm². Here, the number 16, which is the number of conductive particlesthat are captured, is set as a value between 11 and 20 particles, whichis the lower limit of the preferable numerical value of particles to becaptured and will be described below. This is therefore considered to bea numerical value suitable for finding conditions under which theconduction stability can be easily secured. In this way, when the numberof conductive particles that are captured is greater (in this case, 16particles) than the number of conductive particles on the latticearrangement axis (as described above, the number of conductive particleson the lattice arrangement axis in this case is 15 particles), thenumber of conductive particles that are captured at one terminal isgreater than the total number on the lattice axis in a given direction,so the conductive particles that are captured are present on at leasttwo arrangement axes in the same direction. Thus, when the conductiveparticles disposed on at least two lattice axes are captured, it can beanticipated that the positions of the conductive particles captured atthe terminal will be distanced from one another to a certain degree, andthus the pressure balance can be compared. That is, the conditions forassessing the quality of the pressing of the conductive particles at thetime of connection are established. Note that when used for a COG,problems are unlikely to arise in conduction stability in a case wherethe number of consecutive omissions is from 1 to 20 particles, andproblems are even more unlikely to arise if the number is not greaterthan 15 particles and, in particular, not greater than 10 particles.

Note that with regard to omissions in the standard region, even thestandard region may include omissions which are permissible to a degreethat does not inhibit connection, and the size of such permissibleomissions can be assessed based on the spaces between terminals. Atechnique other than the aforementioned technique of assessing based onthe number of consecutive omissions may be used. For example, the sizeof omissions in the long-side direction of the film (width direction ofthe terminals) are preferably not greater than the total space betweenthe terminals (that is, a omission does not straddle two terminals), andomissions are preferably spaced in the short-side direction of the film(long-side direction of the terminals) by a distance greater than 50% ofthe terminal length. As a result, conductive particles that can becaptured are present at least in regions with less than 50% of theterminal length. When the omissions are as described above, it can beanticipated that the conduction performance will be acceptable fortypical anisotropic conductive connection. Note that when assuming suchomissions, the size of the omissions may be determined by considering arectangle formed by the longest distance between conductive particles indirections parallel to each of the long-side direction of the film andthe short-side direction of the film. When considered in this way, thesize of permissible omissions when applied to a fine-pitch terminal suchas a COG is, for example, preferably not greater than 80 μm, morepreferably not greater than 30 μm, and even more preferably not greaterthan 10 μm in the long-side direction of the film (width direction ofthe terminal). In addition, in the short-side direction of the film(long-side direction of the terminal), it is preferable for a region inwhich at least 50% of conductive particles are captured to remain alongthe terminal length. The size is preferably not greater than 100 μm,more preferably not greater than 50 μm, and even more preferably notgreater than 40 μm. Further, in the case of a FOG with a large terminalwidth, the size is preferably not greater than 400 μm and morepreferably not greater than 200 μm in the long-side direction of thefilm (terminal width direction). Since the short-side direction of thefilm serves as the effective connection area, the size is not greaterthan 50% and preferably not greater than 30% of the short-side directionof the film. Depending on the terminal layout, the numerical valuesdescribed above may be combined appropriately. This is because thepresent invention is not limited to a typical COG or FOG

As illustrated in FIG. 1, cases in which sections 2X with omissions arepresent independently without being continuous, or less than aprescribed number of sections 2X with omissions are connected, are alsoincluded in an interspersed manner. In contrast, when there is a portion2Y including at least a prescribed number of consecutive sections 2Xwith omissions, and this is removed as a nonstandard section, theanisotropic conductive film is cut in the long-side direction so as toremove a strip-like region R including this portion 2Y. Note that inFIG. 1, a region where three consecutive omissions are present is usedas a nonstandard section, but this number of omissions is only anexample.

The presence or absence of such omissions can be observed using animaging apparatus such as an optical microscope, a metallurgicalmicroscope, or a CCD camera. In addition, the presence or absence ofomissions can be discovered by testing the dispersion state ofconductive particles in the anisotropic conductive film 1A using animaging apparatus and an image analysis processing system (for example,WinROOF, Mitani Corporation) in combination, and the positions thereofcan be specified. Note that as an example of an imaging apparatus, anapparatus with a maximum pixel output (H)×(V) of 648×494 and a framerate of from 30 to 60 fps can be applied.

In an anisotropic conductive film for a connection structure in whichthe respective bump areas are relatively large (FOG or the like), asillustrated in FIG. 3, a base material is preferably cut so that atleast ten conductive particles are present in a given region S over atotal width W of an anisotropic conductive film 1C and a length of 200μm in the long-side direction of the anisotropic conductive film, inother words, so that at least ten electrically conductive particles arepresent in a range 200 μm long at a given position over the entirelength of the anisotropic conductive film. This is because in a typicalFOG connection, the bump width is at most around 200 μm. Note that sincethe bump length in a typical FOG connection (or tool width in theconnection) is from 0.3 to 4 mm, the total width W after the cutting ofthe anisotropic conductive film in this case is preferably not greaterthan 4 mm.

From the perspective of increasing the number of conductive particlesthat are captured on a terminal to enhance the connection reliability,the number of conductive particles present in the region S is morepreferably not fewer than 11 and even more preferably not fewer than 20particles. The upper limit is not particularly limited. However, whenthe number of conductive particles captured on a terminal at the time ofanisotropic conductive connection is too large due to an excessivelylarge number of conductive particles present in the region S, the thrustrequired for the pressing jig used in the anisotropic conductiveconnection also increases excessively. In this case, there is a concernthat the degree of pressing may differ excessively between therespective anisotropic conductive connection structures obtained bysuccessive anisotropic conductive connection. Therefore, the number ofconductive particles present in the region S is preferably not greaterthan 50, more preferably not greater than 40, and even more preferablynot greater than 35 particles.

On the other hand, in the second aspect of the method for producing ananisotropic conductive film according to an embodiment of the presentinvention, in an anisotropic conductive film for a connection structurein which the respective bump areas are relatively small (such as a COG),a base material may be cut so that no nonstandard sections includingmore than a prescribed number of consecutive sections 2 x with omissionsin conductive particles with respect to a regular disposition arepresent at an end 1P in the short-side direction of the anisotropicconductive film 1A, thus ensuring that even in a case where there areomissions in conductive particles at the end 1P of the anisotropicconductive film after cutting, no nonstandard sections are present, andpreferably that the conductive particles 2 are present in the prescribeddisposition.

Here, the end 1P of the width in the short-side direction of theanisotropic conductive film 1A is preferably not greater than 20% andmore preferably not greater than 30% of the width in the short-sidedirection of the anisotropic conductive film 1A. This is because in aconnection of an electronic component using an anisotropic conductivefilm, a terminal array of the electronic component is ordinarily presentin a strip-like region not greater than 20% of the width and morereliably a strip-like region not greater than 30% of the width in theshort-side direction from an edge extending in the long-side directionof the anisotropic conductive film. Note that the size of the end 1P maydiffer for the left and right ends in accordance with the layout of theterminals of the electronic components to be connected.

In addition, as illustrated in FIG. 4, when bumps (terminals) 10 arearranged in two rows in an electronic component 12 such as an IC chip tobe subjected to a COG connection, even in a case where nonstandardsections including at least a prescribed number of consecutive omissionsin conductive particles are present in a region in which conductiveparticles are disposed regularly (regular disposition region), whenstandard regions Q in which no nonstandard sections are present areformed with a prescribed width in the short-side direction of theanisotropic conductive film 1 and a prescribed length in the long-sidedirection of the anisotropic conductive film 1, the standard regions Qare aligned with the terminal array 11. In other words, a region Rincluding nonstandard sections, which is included in the anisotropicconductive film 1, is aligned with the region between two rows ofterminals 11 (that is, a region in which no terminals to be connectedare present), and opposing electronic components 12 are anisotropicallyconductively connected with the anisotropic conductive film 1. Thepresent invention also includes a connection structure anisotropicallyconductively connected by such alignment. Note that in FIG. 4, thedistance illustrated is the distance from the end of the electroniccomponent 12 to the inner end of the bump 10. This distance preferablyoverlaps with the width of the standard regions Q. As an alignmentmethod, when attaching a film to glass in the case of a COG, alignmentmay be achieved by moving a stage on which the glass is mounted or bymoving the film side. This alignment method is not limited to the caseof a COG and can also be applied to the production of a FOG or anotherconnection structure. The present invention includes a method forproducing a connection structure including such a step.

More specifically, the length L10 in the long-side direction of eachterminal 10 is typically from 30 to 300 μm, and the range of the lengthL11 between two rows of terminals 11 is from 100 to 200 μm for a smallelectronic component such as an IC chip with a plurality of rows ofbumps (for example, a three-row staggered arrangement) and a relativelysmall short end of the external shape, or from 1000 to 2000 μm for alarge electronic component such as an IC chip with a relatively longshort end of the external shape.

Accordingly, in the anisotropic conductive film 1, no problems willarise in a COG connection as long as the width LR of the region Rincluding nonstandard sections is not greater than the width of thelength L11 between adjacent terminal arrays 11 and the width LQ of thestandard region Q has the length L10 in the long-side direction of theterminal 10, and even in a case where the width LR of the region R ofthe anisotropic conductive film exceeds the length L11 between terminalarrays and the region R partially overlaps with the terminal arrays 11,no problems will arise from the perspective of practical use as long asthe number of conductive particles captured by each terminal 10 as aresult of anisotropic conductive connection is preferably not fewer than10 and more preferably not fewer than 13 particles. For example, whenthe size of the terminal 10 is 100 μm×20 μm, the spacing L11 betweenterminal arrays 11 is 1000 μm, and the number density of conductiveparticles in the standard region Q of the anisotropic conductive film 1is 32000 particles/mm², even in a case where the region R of theanisotropic conductive film overlaps with the terminal 10, a COGconnection can be established without any problems from the perspectiveof practical use as long as the overlapping width is not greater than50% of the length L10 of the terminal 10.

Cutting of the Anisotropic Conductive Film

In the method for producing an anisotropic conductive film according toan embodiment of the present invention, in order to increase theproductivity of the anisotropic conductive film, an anisotropicconductive film in which omissions are essentially unproblematic isproduced by preparing a long body of an anisotropic conductive film witha width of a certain magnitude, confirming omissions in conductiveparticles with the test method described above, preferably alsoconfirming defective sites such as sites of aggregation, and cutting thefilm so that these sites are not included in the anisotropic conductivefilm of a prescribed width, or cutting the film into an anisotropicconductive film of a prescribed width so that sections with omissions ordefective sites such as sites of aggregation are included in theanisotropic conductive film but are at intended positions in theshort-side direction of the anisotropic conductive film. In theproduction process of this anisotropic conductive film, the defectivesections may be marked to record the defective sections.

Connection of Aanisotropic Conductive Films

In the method for producing an anisotropic conductive film according toan embodiment of the present invention, an anisotropic conductive filmin which even in a case where omissions are included, the omissions aresubstantially unproblematic can also be provided by connecting theremaining anisotropic conductive films after the regions containingprescribed omission portions have been cut out.

With an embodiment of the present invention, an anisotropic conductivefilm including not more than a prescribed number of consecutiveomissions in the long-side direction can be obtained inexpensively overthe entire length of a long anisotropic conductive film with a length ofnot less than 5 m and not greater than 5000 m wound around a reel. Inparticular, for a COG, an anisotropic conductive film in which noomissions in conductive particles are present at an end 1P of the widthin the short-side direction of the film can be obtained over the entirelength of a long anisotropic conductive film with a length of not lessthan 5 m and not greater than 5000 m.

Connection Structure

The anisotropic conductive film of an embodiment of the presentinvention can be advantageously employed when anisotropicallyconductively connecting, by heat or light, a first electronic component,such as an FPC, an

IC chip, or an IC module, to a second electronic component, such as anFPC, a rigid substrate, a ceramic substrate, a glass substrate, or aplastic substrate. Additionally, first electronic components can beanisotropically conductively connected by stacking IC chips or ICmodules. Connection structures formed in this way are included withinthe scope of the present invention.

One method for connecting electronic components using the anisotropicconductive film may be as follows, for example. One interface of theanisotropic conductive film is temporarily bonded to a second electroniccomponent such as a wiring board. The one interface is the interfacewhere the conductive particles are present in the vicinity in the filmthickness direction. A first electronic component, such as an IC chip,is mounted on the temporarily bonded anisotropic conductive film, andthermal compression bonding is performed from the first electroniccomponent side. This method is preferable from the standpoint ofincreasing the connection reliability. In addition, a connection mayalso be established using photocuring. Note that from the perspective ofconnection operation efficiency in this connect, the long-side directionof the terminal 10 of the electronic component is preferably alignedwith the short-side direction of anisotropic conductive films 1A and 1B.

EXAMPLES

The present invention will be described in further detail hereinafterusing examples, but the present invention is not limited by theseexamples.

Production of a Transfer Body Original Board for COG

First, an original board for use in the embodiments was produced asfollows. Specifically, a nickel plate with a thickness of 2 mm wasprepared, and cylindrical convexities (outer diameter: 4 μm, height: 4μm, center-to-center distance: 6 μm) were formed in a hexagonal latticepattern in a square region 50 cm on each side so as to produce atransfer body original board with a convexity surface density of 32000convexities/mm².

Production of Film-Like Original Board

Next, a polyethylene terephthalate base material film 50 cm wide and 50μm thick was prepared, and a photocurable resin composition containing100 parts by mass of an acrylate resin (M208, Toagosei Co., Ltd.) and 2parts by mass of a photopolymerization initiator (IRGACURE 184, BASFJapan) was applied to the base material film to a film thickness of 30μm.

The nickel transfer body original board was pressed into the obtainedphotocurable resin composition film from the convex surface thereof, andphotoirradiation was performed from the base material film side with ahigh-pressure mercury lamp (1000 mJ) to form a photocurable resin layerin which the convexities of the transfer body original board weretransferred as concavities. This operation was continuously repeatedwhile aligning the unit with the long-side direction of the basematerial film to obtain a film-like original board of approximately 10 min which the convexities of the transfer body original board weretransferred as concavities. Concavities corresponding to the convexitypattern of the transfer body original board were arranged in a hexagonallattice form on the obtained film-like original board.

One thousand regions of 1 mm² of the obtained film-like original boardwere discretionarily selected, and the number of concavities in eachregion was counted with an optical microscope. The total number countedin each region was then divided by the total area of the regions tocalculate the concavity surface density. As a result, the concavitysurface density was 32000 concavities/mm², which was the same as thesurface density of the convexity pattern of the transfer body originalboard.

Production of COG Compatible Anisotropic Conductive Film

Filling Film-Like Original Board with Conductive Particles

Metal-coated resin particles (Sekisui Chemical Co., Ltd., AUL703,average particle diameter: 3 μm) were prepared as conductive particles,and after these conductive particles were scattered a plurality of timesover the surface of the film-like original board, the conductiveparticles were wiped away with a cloth so as to fill the concaveportions of the film-like original board cut out to 30 cm in the lengthdirection with the conductive particles. The cutting locations were atotal of five sections at the starting point, the end point, and threelocations including a point between the starting point and the endpoint. Here, to ensure that conductive particles that do not fill theconcavities are present on the resin mold, the number of conductiveparticles to be scattered or the number of times the particles werescattered was adjusted to obtain a region in which the conductiveparticles were in a prescribed omission state.

Production of Film for Insulating Resin Layer and Film for SecondInsulating Resin Layer

To determine a resin formula suitable for COG, a film for an insulatingresin layer (thickness: 4 μm) and a film for a second insulating resinlayer (thickness: 14 μm) were respectively produced with a size of 20×30cm from insulating binders A1 to A4 and insulating binder B by mixingthe resin compositions of the formulas illustrated in Table 1, applyingthe resin compositions to PET films subjected to release treatment, anddrying the films.

TABLE 1 (Part by mass) A1 A2 A3 A4 Insulating Phenoxy resin (YP-50,Nippon Steel & 50 45 40 37 binders Sumikin Chemical Co., Ltd.) A1 to A4Silica filler (Aerosil R805, Nippon 20 10 10 8 Aerosil Co., Ltd.) Liquidepoxy resin (jER828, Mitsubishi 25 40 45 50 Chemical Corporation) Silanecoupling agent (KBM-403, 2 2 2 2 Shin-Etsu Chemical Co., Ltd.) Thermalcationic polymerization initiator 3 3 3 3 (SI-60L, Sanshin ChemicalIndustry Co., Ltd.) Insulating Phenoxy resin (YP-50, Nippon Steel & 40binder B Sumikin Chemical Co., Ltd.) Silica filler (Aerosil R805, NipponAerosil 5 Co., Ltd.) Liquid epoxy resin (jER828, Mitsubishi 50 ChemicalCorporation) Silane coupling agent (KBM-403, 2 Shin-Etsu Chemical Co.,Ltd.) Thermal cationic polymerization initiator 3 (SI-60L, SanshinChemical Industry Co., Ltd.)

Transfer of Conductive Particles to Insulating Resin Layer

The film for an insulating resin layer described above was applied tothe cut out film-like original board that was filled with conductiveparticles under prescribed positions while aligning the film so that thelengths in the long-side direction matched and so that the widthdirection included the vicinity of the central portion of the film-likeoriginal board, and this was pressed at 60° C. and 0.5 MPa to transferthe conductive particles. The film for an insulating resin layer wasthen peeled from the film-like original board, and the conductiveparticles on the film for an insulating resin layer were pressurized(pressing conditions: 60 to 70° C., 0.5 MPa) to press the particles intothe film for an insulating resin layer. The film for a second insulatingresin layer was further laminated on the conductive particle transfersurface. This was performed at five points of the cut out film-likeoriginal board to produce anisotropic conductive films (ACF1 to ACF4)with conductive particles embedded in the state illustrated in FIG. 8.In this case, the embedding of the conductive particles was controlledby the pressing conditions. When the embedded state of conductiveparticles was observed using the five points of the film-like originalboard cut out to 30 cm in the long-side direction prepared in this wayas a single set, the concavities were all observed in a single setaround the exposed portions of the embedded conductive particles ordirectly above the embedded conductive particles, as illustrated inTable 2. In addition, the film shape of ACF4 could not be maintainedwhen the conductive particles were pressed into the film. It was thusunderstood that ACF1 to ACF3 can be applied to COG Note that theembedded state of the conductive particles was confirmed before theinsulating binder B was laminated. In addition, omissions in conductiveparticles were observed and confirmed for ACF1 to ACF3 by analyzingimages obtained with a CCD image sensor using image analysis software(WinROOF, Mitani Corporation). As a result, a plurality of omissions,including not more than 5 consecutive omissions in the length directionof the film (maximum length of the distance between particles: notgreater than 33 μm, total of the bump width and gap between bumpsdescribed below: smaller than 38 μm) and not more than 7 omissions inthe width direction (maximum length of the distance between particles:not greater than 45 μm), were present. The rectangular region of 33 μmin the length direction of the film and 38 μm in the width direction ofthe film can be considered the permissible omissions. Accordingly, casesin which each dimension is smaller than this are recognized aspermissible omissions. Note that omissions in the width direction werepresent with spacing therebetween by a bump length of not less than 50μm.

TABLE 2 COG evaluation ACF1 ACF2 ACF3 ACF4 Resin composition A1, B A2, BA3, B A4, B Film shape after pressing of OK OK OK NG conductiveparticles Conductive particle diameter: D 3 3 3 3 (μm) Disposition ofconductive Hexagonal Hexagonal Hexagonal Hexagonal particles latticelattice lattice lattice Center distance of closest 6 6 6 6 conductiveparticles (μm) Thickness Insulating resin binder 4 4 4 4 (μm) layer(L_(a)) Insulating adhesive 14 14 14 14 layer La/D 1.3 1.3 1.3 1.3Minimum Insulating resin binder 8000 2000 1500 800 melt layer viscosityInsulating adhesive 800 800 800 800 (Pa · s) layer Total melt viscosity1200 900 900 800 Viscosity Insulating resin binder 12000 3000 2000 1100at 60° C. layer (Pa · s) Embedded state of conductive particlesEmbedding rate (100 × Lb/D)% >80 >95 >95 — Exposed diameter Lc (μm) <2.8<2.5 <2.5 — Presence or absence of Present Present Present — concavities(3b, 3c) Maximum depth Le of <50% <50% <50% — concavities (3b, 3c)(Ratio with respect to conductive particle diameter D) Maximum diameterLd of <1.3 <1.3 <1.3 — concavities (3b, 3c) (Ratio with respect toconductive particle diameter D)Production of Anisotropic Conductive Film for COG Taking intoConsideration Omissions in Conductive Particles

Next, slits with a width of 1.8 mm were formed so that the “conductiveparticle omission states” (see FIGS. 4 and 10: LQ (μm), LR (μm), LQ/W(%), LR/W (%)) of Examples 1 to 4 and Comparative Example 1 shown inTable 3 were reflected. Note that when not obtained, three types of eachanisotropic conductive film were produced by repeating the productionoperations of ACF1 to ACF3 for each of the examples and the comparativeexample while adjusting the scattered amount of conductive particles orthe like. For the anisotropic conductive films of each of the examplesand the comparative example, a slit with a width of 1.8 mm was formed sothat the position of LR (width of nonstandard section (region in whichno conductive particles are present)) was the center of the film. Here,a nonstandard section includes a region a rectangular region in whichany one edge is large and no conductive particles are present in arectangular region of permissible omissions with a size of 33 μm in thefilm length direction and 38 μm in the film width direction, or a regionto which the rectangular region of permissible omissions described aboveapproaches within 50 μm in the width direction.

TABLE 3 Example Example Example Example Comparative (Unit) 1 2 3 4Example 1 Distance between IC (μm) 1000  1000  1000  1000  1000  bumparrangements (μm) Distance V between (μm) 300 300 300 300  300 IC endand bump end (FIG. 10) (μm) Length LQ (μm) of (μm) 600 450 400 350  140> standard region (one side) in film width direction LR (μm) 600 9001000  1100  1600< LQ/W (%)  33  25  22 19    7.7< LR/W (%)  33  50  5661  89 Ratio of long-side (%)  0  0  0 50 100 direction of terminals notin LR Number of conductive  13<  13<  13<  13<  10> particles capturedby a terminal capturing minimum number of conductive particles Initialconduction test Good Good Good Good Poor results

Evaluation 1 for COG

The conduction properties (initial conductivity and conductionreliability) of connection structures obtained by forming COGconnections using the three types of anisotropic conductive filmsproduced in each of Examples 1 to 4 and Comparative Example 1 weretested and evaluated as follows.

Initial Conductivity

Using the following IC for evaluation (see FIG. 10) and a glasssubstrate as electronic components to be subjected to COG connection,the anisotropic conductive film to be evaluated was interposed betweenthe IC for evaluation and the glass substrate and pressurized whileheating (180° C., 60 MPa, 5 sec) to obtain each connected object forevaluation. In this case, the components were joined so that thelong-side direction of the anisotropic conductive film and theshort-side direction of the bumps were aligned and so that a pair ofstandard regions of the anisotropic conductive film were positioned atboth ends in the short-side direction of the IC chip. The conductionresistance of the obtained connection structure was measured with afour-terminal method (JIS K7194) using a digital multimeter (34401A,Agilent Technologies Japan). For practical purposes, the resistance ispreferably not greater than 2 Ω.

Conduction Reliability

After the connection structures used for the measurement of initialconduction resistance were placed in a thermostatic chamber at 85° and85% humidity for 500 hours, the conduction resistance was once againmeasured. For practical purposes, the resistance is preferably notgreater than 5 Ω.

IC for Evaluation

IC outer shape: 1.6 mm (width)×30.0 mm (length)×0.2 mm (thickness)

Gold bumps: 15 μm (height)×20 μm (width)×100 μm (length)

(One thousand gold bumps were arranged at the end in the width directionof the IC outer shape along the long-side direction of each IC outershape with a gap of 18 μm between bumps. The distance between gold bumparrangements was 1000 μm.)

Note that FIG. 10 is a plan view of the IC for evaluation 100 from thebump formation surface side. Symbol 101 is a bump, and G is the gapbetween bumps. Symbol 102 represents the distance between bumparrangements. The regions A and B enclosed by dotted lines correspond tostandard regions of the anisotropic conductive film, and the region Cinterposed therebetween corresponds to a nonstandard region of theanisotropic conductive film (region where no conductive particles arepresent). In addition, V represents the distance between the edge andbump end in the short-side direction of the IC chip.

Glass Substrate

Glass material: 1737F available from Corning Inc.

Dimensions: 30 mm×50 mm

Thickness: 0.5 mm

Terminal: ITO wiring

Evaluation Criteria

For the connection structures used in measurements, cases in which theinitial conduction resistance was not greater than 2 Ω and theconduction resistance after conduction reliability tests was not greaterthan 5 Ω at all of the terminals were evaluated as “good”, and othercases (cases with even a single bump deviating from the ranges describedabove) were evaluated as “poor”. The obtained results are shown in Table3.

As shown in Table 3, the connection structures produced using the threetypes of anisotropic conductive films of each of the Examples 1 to 4exhibited good conduction properties, but in the case of ComparativeExample 1, the standard regions were too small, and thus the conductionproperty was evaluated as poor.

Note that it was found that even when a omission region touches a partof a terminal, there are no problems from a practical standpoint as longas at least 10 and preferably at least 13 conductive particles arecaptured on the terminal. It was also found that although a omissionregion may touch a terminal arrangement, the degree of this fluctuatesdepending on the terminal area and should be adjusted appropriately(Example 4). In light of the above examples, it was determined that theratio of a standard region to the film width may be not less than 13%,preferably not less than 20%, and more preferably not less than 33%.

Production of Transfer Body Original Board for FOG, Film-Like OriginalBoard for FOG, and FOG Compatible Anisotropic Conductive Films

A transfer body original board for FOG, a film-like original board forFOG, and anisotropic conductive films in which conductive particles areembedded in the state illustrated in FIG. 8 (ACF5 to ACF8 (see, Table5)) were produced by repeating the production process for a COGcompatible anisotropic conductive film with the exception of using thebinders shown in Table 4 instead of the insulating resin binders shownin Table 1 and selecting conditions so that the conductive particlesassume a prescribed omission state. In this case, the embedded state ofthe conductive particles was controlled by the pressing conditions. As aresult, concavities were observed as shown in Table 5 around the exposedportions of the embedded conductive particles or directly above theembedded conductive particles. This was confirmed before the insulatingbinder D was laminated. Note that the film shape of ACF8 could not bemaintained when the conductive particles were pressed into the film. Itwas thus found that ACF5 to ACF7 can be applied to FOG

In addition, omissions in conductive particles were observed andconfirmed for ACF5 to ACF7 by analyzing images obtained with a CCD imagesensor using image analysis software (WinROOF, Mitani Corporation). As aresult, a film with a omission state of a degree in which at least 10conductive particles were necessarily present within a range of notgreater than 200 μm in the long-side direction of the film (widthdirection of the terminal) (Example 5), and a film with a omission statein which only 1 or 2 conductive particles were present (ComparativeExample 2), were obtained.

TABLE 4 (Part by mass) C1 C2 C3 C4 Insulating Phenoxy resin (YP-50,Nippon Steel 55 45 25 5 binders & Sumikin Chemical Co., Ltd.) C1 to C4Phenoxy resin (FX-316ATM55, Nippon 20 40 Steel & Sumikin Chemical Co.,Ltd.) Bifunctional acrylate (A-DCP, Shin- 20 20 20 20 Nakamura ChemicalCo., Ltd.) Bifunctional urethane acrylate oligomer 25 35 35 35(UN-9200A, Negami Chemical Industrial Co., Ltd.) Silane coupling agent(A-187, Momentive 1 1 1 1 Performance materials Inc.) Phosphoric acidmethacrylate 1 1 1 1 (KAYAMER PM-2, Nippon Kayaku Co., Ltd.) Benzoylperoxide (Nyper BW, 5 5 5 5 NOF Corporation) Insulating Phenoxy resin(FX-316ATM55, Nippon 50 binder D Steel & Sumikin Chemical Co., Ltd.)Bifunctional acrylate (A-DCP, Shin- 20 Nakamura Chemical Co., Ltd.)Bifunctional urethane acrylate oligomer 30 (UN-9200A, Negami ChemicalIndustrial Co., Ltd.) Silane coupling agent (A-187, Momentive 1Performance materials Inc.) Phosphoric acid methacrylate 1 (KAYAMERPM-2, Nippon Kayaku Co., Ltd.) Benzoyl peroxide (Nyper BW, 5 NOFCorporation)

TABLE 5 FOG evaluation ACF5 ACF6 ACF7 ACF8 Resin composition C1, D C2, DC3, D C4, D Film shape after pressing of OK OK OK NG conductiveparticles Conductive particle diameter: D 3 3 3 3 (μm) Disposition ofconductive particles Hexagonal Hexagonal Hexagonal Hexagonal latticelattice lattice lattice Center distance of closest 6 6 6 6 conductiveparticles (μm) Thickness Insulating resin binder 4 4 4 4 (μm) layer (La)Insulating adhesive layer 14 14 14 14 La/D 1.3 1.3 1.3 1.3 MinimumInsulating resin binder 8000 2000 1500 800 melt layer viscosityInsulating adhesive layer 800 800 800 800 (Pa · s) Total melt viscosity1200 900 900 800 Viscosity Insulating resin binder 12000 3000 2000 1100at 60° C. layer Embedded state of conductive particles Embedding rate(100 × Lb/D)% >80 >95 >95 — Exposed diameter Lc (μm) <2.8 <2.5 <2.5 —Presence or absence of Present Present Present — concavities (3b, 3c)Maximum depth Le of <50% <50% <50% — concavities (3b, 3c) (Ratio withrespect to conductive particle diameter D) Maximum diameter Ld of <1.3<1.3 <1.3 — concavities (3b, 3c) (Ratio with respect to conductiveparticle diameter D)Production of Anisotropic Conductive Film for FOG Taking intoConsideration Omissions in Conductive Particles

Next, five anisotropic conductive films per set (ACF5 to ACF7) cut to20×30 cm were respectively slit to a width of 2 mm. Films in which atleast 10 conductive particles were necessarily present within a range of200 μm in the long-side direction of the film (width direction of theterminal) over a 20 mm region of films extracted from 5 discretionarilyselected locations (total of 25 locations for 5 films) of these filmswere prepared as anisotropic conductive films of Example 5. In addition,an anisotropic conductive film of Comparative Example 2 was obtained byrepeating the same operation with the exception of including a regionwith 1 or 2 conductive particles.

Evaluation 2 for FOG

The conduction properties (initial conductivity and conductionreliability) of connection structures obtained by forming FOGconnections using the three types of anisotropic conductive filmsproduced in each of Example 5 and Comparative Example 2 were tested andevaluated as follows.

Initial Conductivity

Using the following FPC for evaluation and a glass substrate aselectronic components to be subjected to FOG connection, eachanisotropic conductive film to be evaluated was cut out and interposedso that the previously arbitrarily extracted 25 sections were betweenthe FPC for evaluation and the glass substrate, and then waspressed-heated (180° C., 4.5 Mpa, 5 seconds), whereby each connectedobject for evaluation was obtained. In this case, the components werejoined so that the long-side direction of the anisotropic conductivefilm and the short-side direction of the bumps were aligned. Theconduction resistance of the obtained connection structure was measuredwith a four-terminal method (JIS K7194) using a digital multimeter(34401A, Agilent Technologies Japan). For practical purposes, theresistance is preferably not greater than 2 Ω.

Conduction Reliability

After the connection structures used for the measurement of initialconduction resistance were placed in a thermostatic chamber at 85° and85% humidity for 500 hours, the conduction resistance was once againmeasured. For practical purposes, the resistance is preferably notgreater than 5 Ω

FPC for Evaluation

Tin-plated copper wiring (L/S=200/200) with a thickness of 8 μm and apitch of 400 μm formed on a polyimide substrate with a thickness of 38μm

Glass Substrate

Glass material: 1737F available from Corning Inc.

Dimensions: 30 mm×50 mm

Thickness: 0.5 mm

Terminal: ITO wiring

Evaluation Results

For the connection structures used in measurements, cases in which theinitial conduction resistance was not greater than 2 Ω and theconduction resistance after conduction reliability tests was not greaterthan 5 Ω were evaluated as “good”, and other cases were evaluated as“poor”. As a result, the conduction properties of the connectionstructures produced using the three types of anisotropic conductivefilms of Example 5 were good, whereas the connection structure producedusing the anisotropic conductive film of Comparative Example 2 had agreater amount of nonstandard regions present in the regular dispositionregion than in Example 5, and thus the conduction properties wereevaluated as poor.

INDUSTRIAL APPLICABILITY

The anisotropic conductive film of an embodiment of the presentinvention includes a regular disposition region in which conductiveparticles are disposed regularly in an insulating resin binder, and thelength is 5 m or greater. Moreover, a standard region including nosections with more than a prescribed number of consecutive omissions inconductive particles is present in the regular disposition region over aprescribed width in a short-side direction of the anisotropic conductivefilm and at least a prescribed length in a long-side direction of theanisotropic conductive film. Therefore, even in a case where omissionsare present in a prescribed regular disposition of conductive particles,the film can be used for anisotropic conductive connections insubstantially the same manner as an anisotropic conductive film withoutomissions. The anisotropic conductive film of an embodiment of thepresent invention is useful as a junction member for low-costanisotropic conductive connection.

REFERENCE SIGNS LIST

-   1, 1A, 1B, 1C Anisotropic conductive film-   1P End of the width in the short-side direction of the anisotropic    conductive film-   2, 2 a, 2 b, 2 c, 2 d Conductive particle-   2 t Apical part of conductive particle-   2X Omission of conductive particle-   2Y Portion including consecutive omission-   3 Insulating resin binder-   3 a Surface of insulating resin binder in central portion between    adjacent conductive particle-   3 b, 3 c Concavity-   3 p Tangential plane-   4 Insulating adhesive layer-   5 Repeating unit-   10 Bump, terminal-   11 Terminal array-   12 Electronic component-   D Average particle diameter of conductive particle-   L1 Lattice axis-   La Thickness of insulating resin binder-   Q Standard region-   R Region including nonstandard section-   S Discretionarily selected region

1. An anisotropic conductive film at least 5 m long having a regulardisposition region in which conductive particles are disposed regularlyin an insulating resin binder, wherein a standard region including nosections with more than a prescribed number of consecutive omissions inconductive particles is present in the regular disposition region over aprescribed width in a short-side direction of the anisotropic conductivefilm and at least a prescribed length in a long-side direction of theanisotropic conductive film.
 2. The anisotropic conductive filmaccording to claim 1, wherein the regular disposition region and thestandard region are aligned.
 3. The anisotropic conductive filmaccording to claim 1, wherein nonstandard sections are present, thenonstandard sections being sections including at least a prescribednumber of consecutive omissions in conductive particles.
 4. Theanisotropic conductive film according to claim 1, wherein ten or moreconductive particles are present in a discretionarily selected region of200 μm in the long-side direction over the entire width of theanisotropic conductive film.
 5. The anisotropic conductive filmaccording to claim 1 including a standard region along at least an endregion in the short-side direction of the anisotropic conductive film.6. The anisotropic conductive film according to claim 1, wherein theanisotropic conductive film is a wound body which is wound around areel.
 7. A method for producing an anisotropic conductive film at least5 m long, wherein a wide base material of an anisotropic conductive filmin which conductive particles are disposed regularly in an insulatingresin binder is cut in a length direction such that no nonstandardsections including at least a prescribed number of consecutive omissionsin conductive particles are included in a regular disposition, or suchthat nonstandard sections are at intended positions in a short-sidedirection of the film.
 8. A method for producing an anisotropicconductive film at least 5 m long, wherein nonstandard sectionsincluding at least a prescribed number of consecutive omissions inconductive particles are removed from an anisotropic conductive filmincluding a standard disposition region in which conductive particlesare disposed regularly in an insulating resin binder, and theanisotropic conductive films after removal are connected.
 9. A methodfor producing a connection structure, comprising establishing ananisotropic conductive connection between terminal arrays of a firstelectronic component and a second electronic component by subjecting afirst electronic component including a terminal array and a secondelectronic component including a terminal array to thermocompressionbonding via an anisotropic conductive film including a standarddisposition region in which conductive particles are disposed regularlyin an insulating resin binder, wherein an anisotropic conductive film inwhich a standard region including no sections with more than aprescribed number of consecutive omissions in conductive particles isformed in the standard disposition region over a prescribed width in ashort-side direction of the anisotropic conductive film and a prescribedlength in a long-side direction of the anisotropic conductive film isused as an anisotropic conductive film; and the standard region isaligned with the terminal arrays of the electronic components.
 10. Themethod for producing a connection structure according to claim 9,wherein when the first electronic component and the second electroniccomponent respectively have a plurality of terminal arrays and thestandard regions are formed in an array on the anisotropic conductivefilm, a region between adjacent standard regions is aligned with aregion between terminal arrays.